The present invention relates in general to shock mounted filament type vehicle lamps adapted to perform stop and/or turn and tail signalling functions, and more particularly to vehicle lamps having a single shock mounted filament capable of performing dual functions such as low intensity tail lamp functions and bright or higher intensity stop and/or turn signalling.
Heretofore, a number of signalling lamps for vehicles, such as automobiles, trucks, trailers and the like, have been provided which are capable of performing both relatively low intensity tail lamp functions signalling the location of portions of the vehicle, and higher intensity stop and/or turn signalling functions wherein the tail lamp or lamp glows more brightly. However, most of such prior art dual function vehicle signal lamps have used two filaments, one of which is energized for the lower intensity signalling functions and the other of which is energized for the higher intensity signal functions. Earlier U.S. Pat. No. 1,595,535 to Wood disclosed a headlight bulb with a single filament, having a resistance wire connected between one end of the filament and a connection terminal so that the resistance wire can be placed in circuit with the filament to operate at reduced intensity in one operating mode and the resistance wire could be bypassed to cause the lamp to operate at a higher intensity level. Also, vehicle lamp systems involving complicated circuitry for providing variable intensity automobile lighting with a single filament have also been proposed, as in U.S. Pat. No. 3,040,207 To Grontkowski, but improvements in signalling lamps to avoid the complicated circuitry of the above mentioned patent in vehicle lamps designed particularly for the severe shock loads encountered by signalling lamps on trucks, trailers and the like for stop and/or turn and tail signalling functions are desired, particularly to eliminate the minor or low intensity filament present in such dual function signalling or illuminating lamps designed for this purpose which become very brittle and susceptible to shock and/or high impact failures, and thereby extend the life of lamps used for such purposes. Also, it is desired to reduce thermal shock on the filament, which is accomplished in the present invention by heating it continuously while the vehicle lights are activated and render the lamp interchangeable with conventional lamps.
The problem of short life in relation to lamp failure in the automotive industry is especially acute in the trucking industry, where the lamps are subject to frequent and intense shock and high-impact forces. The incorporation of a shock mount such as proposed in prior U.S. Pat. No. 3,327,110 granted June 20, 1967 to the assignee of the present application has succeeded in extending the life of such automotive lamps for trucking applications manyfold over that of a conventional rigid mount. However, the problem of the minor filament in dual filament lamps designed to be energized for low intensity or dim signalling functions being too fragile has still been present and has led to premature failure due to shocks and high-impact stresses.
An object of the present invention, therefore, is the provision of a novel single filament lamp assembly designed to perform the usual functions of dual filament lamps for use in the vehicle industry for stop and/or turn and/or tail signalling or illuminating functions by elimination of the minor filament present in such prior signalling lamps through the use of electronics while still enabling the single filament bulb to perform the same functions as dual filament bulbs.
Another object of the present invention is the provision of a novel single filament lamp assembly for vehicle signalling applications as described in the immediately preceding paragraph, wherein the electronics permitting the single filament to serve the functions of two filaments is rigidly incorporated in a solid-state electronic system fixed in the rim or peripheral portion of the reflector and lamp housing member, which lends itself to ease of installation and economical construction.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.